Multilayer materials comprising a curable molding material layer have flexibility before curing and, therefore, can be worked according to an arbitrary shape and size and, after working, applied to substrates with ease. Further, after curing, they show good mechanical, chemical, electrical and other fundamental performance characteristics comparable to those of fiber-reinforced plastics.
If multilayer materials comprising such a curable molding material layer become available which are capable of being easily worked and applied, making it possible to secure an ample operating time, showing sufficient adhesiveness to adapt to various surface conditions and complicated shapes and forms of various substrates, such as metals, plastics, rubbers, glass, ceramic ware, stone and wood, and satisfactorily suppressing the incidence of troubles due to poor adhesion to substrates, they will be useful, in various fields of application, as structural members, pipes, linings and so forth in various buildings, machines, automobiles, ships, household utensils and the like, and as reinforcing materials for reinforcing or repairing them.
In Japanese Kokai Publication Sho-59-1250, there is disclosed a method of applying a prepreg to steel sheet which comprises coating a curable prepreg with a curable and lipophilic primer, then causing the coated surface to bond closely to a steel sheet and, thereafter, curing the prepreg and primer. This application method can suppress the occurrence of poor prepreg-steel sheet adhesion to a certain extent by causing the prepreg to swell a little by means of the primer.
However, there is the possibility of failure to secure sufficient adhesion to certain substrates. Further, since the prepreg and/or primer may cure during application, the application time is limited and/or the prepreg may fail to stick to substrates sufficiently, hence the occurrence of poor adhesion may not be suppressed to a satisfactory extent. Furthermore, the necessity of using a primer in the step of application makes the relevant application work complicated.
In Japanese Kokai Publication Sho-63-186744, there is disclosed a photocurable prepreg having a transparent sheet bonded to one side thereof. A feature of this photocurable prepreg is that the surface of the cured product becomes smooth and good-looking owing to the transparent sheet. However, primer application is necessary for adhering to a substrate and, even by primer application, there is still the possibility of failure to secure sufficient adhesion to certain substrates. Further, the application work is complicated.
In Japanese Kokai Publication Sho-57-99375, there is disclosed a method of reinforcing thin steel sheet which comprises adhering a curable molding material layer to a thin steel sheet using a photocurable epoxy vinyl ester resin containing a specific dibasic acid and/or oligoester in the resin skeleton, followed by curing by exposure to light. This reinforcing method can indeed improve the adhesion strength of the curable molding material layer to the thin steel sheet to a certain extent but sufficient adhesion may not be secured for certain substrates. Further, the method may fail to prevent poor adhesion sufficiently and the application work is complicated.
It is an object of the present invention, which has been made in view of the above-described state of the art, to provide a multilayer material which is excellent in applicability, can fully prevent the occurrence of poor adhesion to various substrates, can give cured products having sufficient fundamental performance characteristics and, further, can bring about improvements in adhesion strength and durability, among others, hence can be applied in various fields of purpose.
The present invention provides a multilayer material comprising a light-shielding layer (a), a curable molding material layer (b), a tacky layer (c) and a releasing layer (d), with one side of the curable molding material layer (b) having the light-shielding layer (a) and the other side having the tacky layer (c) and releasing layer (d) in that order from the inside.
The present invention also provides a reinforcing material comprising the multilayer material.